SMART-1 makes lunar orbit

Europe has reached the moon

The SMART-1 probe has entered its lunar orbit, and the history books as the first European mission to have done so.

Professor David Southwood, director of science for the European Space Agency (ESA), said: "Europe has arrived at the Moon, we're in lunar orbit."

The craft arrived at its destination thirteen months after launching from Earth. Although the moon is only 380,000km away in a straight line, SMART-1 orbited the Earth more than 300 times, and travelled 84m km. In fact, its journey comparable in length to an interplanetary cruise: at its closest, Venus is just 40m km away from us, and Mars is 35m km.

SMART-1 slotted into orbit at an altitude of 5000km, and will settle into its final orbit over the next few months. Its ion-propulsion engine will fire continuously for the next four days to help it stabilise. By January, it should be in an elliptical orbit, passing the moon at a distance of 300km over the South pole, and 3000km over the North pole.

On its journey it carried deep-space communication tests including a study of feasibility of pointing a laser beam from Earth at a moving, distant, spacecraft. It is now the first electrically powered craft to complete gravity assist manoeuvres, the ESA says.

SMART-1 also tried out new techniques for allowing a spacecraft autonomous control of its flight. The OBAN experiment tested how well navigation software on ground computers could calculate the position and velocity of the spacecraft using images of celestial objects taken by the AMIE camera on SMART-1 as references.

Once its orbit is finalised, SMART-1 will scan the lunar surface for resources, particularly water, for future, manned, missions. Astronomers hope the data it sends back to Earth will shed light on the formation of Earth's only satellite. ®

Bootnote:

Some readers were upset by our whimsical suggestion that a mini could drive to the moon in less time, given a suitable motorway. For you, then, we offer the following statistical meanderings:

SMART-1 clocked up 332 orbits around Earth, so that the distance it travelled was rather further than the 380,000 linear km to the moon. It fired its engine 289 times during the cruise phase, operating for a total of about 3700 hours, and it actually only used 59 kilograms of its xenon propellant.